International patent application WO 81/00051, published on Jan. 22, 1981, describes an article impervious to liquids intended for perfuming ambient air or closed spaces, characterized in that it contains a perfuming composition enriched in weak polarity substances, odoriferous or not, and in that it possesses at least one polymeric wall enabling the diffusion towards the exterior of active odorant ingredients.
French patent application FR-A 2 091 855, published Jan. 21, 1972, discloses a device for the continuous diffusion of vapors from purifying agents, which comprises a permeable wall in macromolecular material, one face of which is in contact with the volatile purifying agent, the latter impregnating a fibrous mass which is covered by the permeable wall.
French patent application FR-A 2 336 946, published Jul. 29, 1977, relates to a slow diffusion air-freshening system which comprises an enclosure and a perfume contained in said enclosure, at least one surface of said enclosure being a polymer film. Also in this system, the perfume is impregnated on a support such as silica, talc, glasswool or blotting paper.
U.S. Pat. No. 3,578,545, published May 11, 1971, discloses a flexible stratified device releasing a perfume and comprising a perfume impregnated fabric, enclosed in a porous plastic film, permeable to the perfume vapors.
U.S. Pat. No. 4,161,283, published Jul. 17, 1979, describes a device intended for the continuous diffusion of purifying vapors; said device comprises an exterior wall formed of a polymeric material allowing a molecular diffusion and an impermeable interior wall. The exterior wall is also covered by an impermeable sheet capable of preventing the diffusion of the active volatile substances during storage.
An analogous device is described in U.S. Pat. No. 4,285,468, published Aug. 25, 1981.
Since the purifying or freshening articles described in the prior art consist all of a system comprising a polymeric diffusion wall, they must posses a device intended for preventing the diffusion of the active perfuming substances into the environment during storage.
To this end, International patent application WO 81/00051 describes a means consisting in the application of a polymeric sheet of the Surlyn.RTM. type (origin: Du Pont de Nemours) onto the walls through which diffusion normally occurs. Such a polymeric sheet may be made to cling through thermal welding to polyethylene or polypropylene and be pulled off just before use. Another means to the same end is the use of aluminium sheets welded to polypropylene foam.
A problem rises however upon long storage of such devices before sale: owing to the diffusion of the perfume vapors through the polymeric material walls of the package, considerable loss of the initial amount of active substance has been observed. In order to obviate this disadvantage, a multi-chamber device has been developed by the instant applicant (see International patent application WO 82/02700, published Aug. 19, 1982). In a device of this type, the active perfuming solution is kept in a compartment whose walls are impermeable to the perfume vapors and which has a joint that can be broken under the effect of an external pressure. Just before use, once the walls of said joint are broken, the solution passes into a compartment whose walls are made of a polymeric material permeable to the perfume vapors which can then diffuse evenly into the surrounding atmosphere.
Such a device is very efficient in practice, but its manufacture requires a sophisticated apparatus and a rigorous assembling technique.
Patent application FR-A 2 539 492 proposes, as a remedy to such inconvenients, a novel solution based on a simple technique. It describes, in effect a direct assemblage by welding of a thin paper layer to the external wall of the polymeric membrane through which diffuse the vapors of the active substance. This thin paper layer is then covered by a polymeric material sheet, for example a material of the Surlyn.RTM. type, polyethylene-based, on which is finally welded a metallic sheet, preferably for example an aluminum sheet.